Pedestal mounted rocker arm assemblies have a rocker arm rotatably mounted on a support pin and the support pin is fixed to the cylinder head through the pedestal. The support pin is also known as a trunnion. Conventionally, the support pin rests on a pedestal, also known as a support block which positions the overall rocker arm assembly away from the cylinder head. One end of the rocker arm is in contact with the push rod while the other end of the rocker arm is in contact with a valve shaft.
Roller bodies, also referred to as radial bearings are conventionally used between the support pin and the rocker arm to facilitate rotational movement of the rocker arm on the support pin and to handle radial loads.
Rocker arm assemblies can also be subject to axial forces or thrust forces. These axial forces occur when certain parts are out of alignment, for example, when the rocker arm pallet and the socket, the lower end of the push rod and the socket, or the valve shaft and the rocker arm pallet are out of alignment. Such rocker arm assemblies are often referred to as “offset rocker arm assemblies”.
Solutions for handling thrust forces in rocker arm assemblies are taught in U.S. Pat. No. 6,694,936 and U.S. Patent Publication No. 2008/0098971.